Weighing apparatus



Oct 9, 1962 J. D. FANN 3,057,421

WEIGHING APPARATUS Filed Aug. 17, 1956 2 Sheets-Sheet l uw! A in l IA\L lilllllHl lll|||||||||llllllmllnnla-v- |||i1||||||||||n|||||||||||||||l||||||||||||||||||||I|||||||||| dame: 7. Fal/7n INVENTOR.

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ATTORNEY 0Ct 9, 1952 J. D. FANN 3,057,421

WEIGHING APPARATUS Filed Aug. 17, 1956 2 Sheets-Sheet 2 daz/Mew Far/W7 INVENTOR.

3,957,421 WEIGEENG APPARATUS James D. Faun, Houston, Tex. Fiied Aug. 17, 1956, Ser. No. 604,725 8 Ciairns. (Cl. 177 149) This invention relates to weighing apparatus and particularly to balances for determing the weight or density of liquids such as drilling fluids.

In controlling the drilling of oil wells, control of the weight or density of the drilling fluid employed is of primary importance. Not only is the weight or density of the drilling fluid of importance in itself, but the weight or density of the drilling fluid is also correlated with other properties of the drilling fluid such as viscosity, thixotropy, concentrations, and plasticity. Control of all of these properties or characteristics is necessary to insure Success of the drilling operation.

In determining the weight or density of the drilling fluid during the drilling of the well, it is necessary that the individual determinations be made rapidly and frequently and near the well site, usually under conditions such that the equipment by means of which the determinations are made is subjected to rugged conditions of weather, uncleanliness, and corrosion.

Drilling fluids being of a thixotropic or jell forming nature it is not generally convenient at a well site to make the density or gravity determinations with equipment not readily adaptable to rapid and frequent cleaning and to the abuses of drilling crews.

It is, therefore, a principal object of the invention to provide apparatus suitable for readily and accurately determining the density and gravity of drilling fluids.

Another object of the invention is to provide such apparatus of rugged design adaptable for use under extreme well site conditions.

Another object of the invention is to provide such apparatus which may be easily calibrated by unskilled operators.

Another object of the invention is to provide such apparatus which is light in weight and readily transportable, pleasing in appearance, and low in cost.

Other objects, uses, advantages, and improvements of the invention will appear from the following description of a preferred embodiment thereof, reference being made to the accompanying drawings, of which:

FIGURE 1 is a side elevation of the apparatus assembled for use;

FIGURE 2 is a plan view of the apparatus of FIG- URE 1, taken at line 2 2 thereof;

FIGURE 3 is an end elevation of the apparatus taken at line 3 3 of FIGURE 1;

FIGURE 4 is a vertical section through the pedestal support, taken at line 4 4 of FIGURE l;

FIGURE 5 is a vertical section taken at line 5 5 of FIGURE l;

FIGURE 6 is a partial side view, partly in vertical section taken at the longitudinal axis of the balance arm, showing the tare weight adjustment;

FIGURE 7 is a vertical section through a central portion of the balance arm, taken at the center thereof, and showing the balance pivot and leveling means; and

FIGURE 8 is a perspective view showing a manner of using the apparatus.

Preferring now in detail to Ithe drawings, a cup 10 is supported by a balance arm 11 integrally formed therewith and extending radially from one side of the cup below the upper circular lip 12 of the cup. Balance arm 11 is of elongated form, there being a rectangularly formed portion 14 next to cup 10, a downward offset 15, and a long cylindrical portion 16 outwardly of the olfset 3,057,421 Patented Oct. 9, 1962 ice from the cup. The cup and balance arm are unitary, preferably being cast of a metal such as aluminum. This one piece construction of the cup and balance arm is very rigid and strong, so that it can be damaged only by severe abuse. It is also important to note that the cylindrical arm portion 16 is streamlined so that strong winds do not seriously affect the accuracy of determinations made with the apparatus. In addition, it is easier to scrape mud and other contamination from the round arm 16 than from a flat-sided arm so that the apparatus is easier to keep clean than is other similar apparatus.

The balance arm 11 is pivotally supported upon a pedestal support 20, which is flared downwardly to provide an enlarged lower ange 21 upon which the pedestal support rests, and diminishes upwardly to a small circular upper end 22. The bottom of cup 10 is above flange 21 when the apparatus is properly balanced. Support 20 has circular horizontal cross sections over its height, the sections having a common vertical axis. Through two opposite edges of ange 21, there are provided vertical screw holes 24, 25, each having an upper screw head recess 26, 27, respectively, screws being inserted through the screw holes to secure the pedestal support upon a Hat surface. The underside of the support is hollow as at 28, the flared upper walls and top of the support being uniform in thickness. A screw 30 is threadingly received through the top of the support, there being a tapped screw hole vertically there through at the center of upper surface 22. The head of screw 30 s screwed flush against the upper surface of hollow opening 28 and between the flared sides of the pedestal support. The threaded end of screw 30 extends above surface 22, to be received into a lower tapped hole in one end of a cylindrical fulcrum 31. Fulcrum 31 has a diameter equal to the diameter of the upper end of pedestal support 20 and upper surface 22 thereof, so that the sides of the fulcrum and support meet flushly. At the upper end of fulcrum 31 there is provided a diametral groove 32 which has a rounded bottom against which a knife edge pivot of the balance arm may be engaged.

The member including the cup 10 and balance arm 11 is provided with a knife edge pivot at the underside of rectangular arm portion 14 and near arm offset 15. The knife edge pivot is provided by one longitudinal edge of a triangular pivot block 35, the knife edge 36, being between two equal faces of the block disposed at an angle of about one to the other, and facing diagonally downwardly. The upper face of the pivot block faces upwardly and intersects both of the lower faces at angles of about 45. The exact cross-section of the pivot block is not critical and the angles between the faces may be varied. A angular groove 37 laterally across 4the lower face of arm portion 14 corresponds in shape with the upper part of the pivot block 35. The upper part of the pivot block is press tted tightly into the groove 37 so that it remains in place but is removeable for repair or replacement. The sides of groove 37 are angular one toward the other corresponding to the angle between the downwardly facing faces of the pivot block so that the pivot block cannot fall or be removed downwardly out of the groove. The press fit of the groove with the upper part of the pivot insures that the pivot block will remain rmly in place during use of the apparatus, without any screws whatever to hold it in place, even though the apparatus is subjected to extremely rough treatment. Knife edge 36 is placed within groove 32 of fulcrum 31 when a weight or gravity determination is to be made, the cup 10 and arm 11 being of such proportions and weights that a balance thereof may be attained by adjustment of a counterweight 40, to be described. Pivot block 35 and fulcrum 31 are preferably made of a hard non-corrodahle material such as strainless steel or other alloy of similar properties so that the pivot edge and groove are not easily damaged.

The knife edge 36 may be said to divide the balance arm 11 into a cup supporting portion at one side of the knife edge and a weight supporting portion at the other side of the knife edge. The weight supporting portion includes the tubular portion 16 carrying externally a counterweight and internally a taring weight as will now be described.

The elongated tubular portion 16 of balance arm 11 is fitted externally with the slidable counterweight 40. Counterweight 40` is cylindrical in form and has an offcenter circular hole 41 therethrough perpendicular to the fiat ends of the cylinder. The hole 41 is of a diameter slightly greater than the diameter of arm portion 16, which -is received through the hole, and thus the counterweight can be slidably moved over the length of the tubular arm portion 16. Arm portion 16 is calibrated over its length, and counterweight 4t) has one of its at ends indicated by an arrow 42 or other mark on the curved side of the counterweight nearest hole 41, so that the at end can be used as a mark in determining the position of the counterweight along the calibrated arm portion.

Tubular arm portion 16 is preferably calibrated with two scales 45 and 46, scale 45 indicating the weight or gravity of drilling fluid in cup as pounds per gallon, and scale 46 indicating the weight or gravity as pounds per cubic foot. These particular scales are provided because they are usually most convenient for the drilling crews use, but other scales may be used and additional scales may be provided if desired. A weight or gravity reading is made by slidingly moving the counterweight 40 along the tubular arm 16 to the position in which the balance arm and cup are balanced, and reading the weight or gravity on Ithe appropriate scale at the point marked by the indicated end of counterweight 40 indicated by arrow 42. The arrow 42 or other mark is automatically positioned above the scales at the top of the arm because of the greater weight of the counterweight at its side away from the off-center hole 41.

Should the tubular arm 16 become covered with dirt or with a crust of mud or dried drilling fluid, the counterweight can be moved along and/or rotated about the arm to scrape it clean.

In making a weight or gravity determination, the cup 10 is always filled to capacity with drilling Huid in order that there will be a constant volume factor upon which the weight and gravity readings may-be based, that is, weights and gravity determinations are always taken of the same volume of drilling Huid. Cup 10 has the upper edge or lip 12 around which fits a top 50 to cover the cup opening. The upper surface of the top (see FIG- URE 3) is flat, and the lower surface of the top is conically beveled, converging upwardly, and has a'small opening 51 therethrough at the apex. Around the conical-lower surface a part of the top is reduced to t snugly Within the top of the cup, while the upper unreduced flange portion 53 of the top ts snugly above the edge 12 of the cup. A constant measured volume of drilling fluid is obtained by filling the cup completely and then forcing down the top 50 until it is seated as described, the excess iuid in the cup flowing out through hole 51 while the top is being forced down so that the cup is full of fluid up to the top 50, with no air spaced therewithin. Before a determination is made the exterior of the cup and top are cleaned by washing or wiping.

Top 50 is preferably made of molded hard rubber, which can be made of accurate form and weight such that top 50 is replaced without necessity of any alteration to the remainder of the apparatus to correct its balance.

At the end of tubular arm portion 16 there is provided threads may extend the full length of the bore. A taring weight in the form of a cylindrical exteriorly threaded plug a slug 57 of shorter length than the bore and threads is screwed into the threads 56 to serve as a weight adjusting means at the end of the balance arm. Plug 57 has a slot 58 at its outer end so that it may be turned and its axial position changed with an ordinary screwdriver. A cap 60 having threaded body 61 and outer overhanging flange 62 is screwed into the end of the bore to close the bore and to protect the plug 57 from corrosion and the like. The flange 62 extends beyond the sides of arm portion 16 so that counterweight 40 is retained thereon by flange 62 and by offset 15. The outer face of the cap 60 has a slot 63 by means of which the cap may be screwed into and out of the threads. It is important to note that once the weight of the balance arm is adjusted by moving plug 57 to the proper position in threads 56, and cap 60 is screwed into the end of the arm, the adjustment will not be disturbed by handling of the apparatus, since access to the plug 57 is blocked by cap 66. Since drilling iluids commonly contain strong corrosive constituents such as sodium hydroxide the er1- closed arrangement for weight adjustment plug 57 is exceedingly important, and it should be further poined out that adjustment of the plug never becomes diicult because the threads 56 are also enclosed.

At the upper face of rectangular arm portion 14 adjacent to offset 15 there is formed a slot 65 which extends toward the cup from the face 66 of the offset 15. The slot 65 has a deeper portion 67 spaced from olfset face 66, there being a narrower offset slot 68 at the end of the deeper slot portion 67 toward face 66. Above the deeper slot portion a groove 70 runs horizontally around the interior of the slot, extending along both Sides of the slot and around its end. A cover 71 corresponding in shape with horizontal section of the slot, has an edge flange 72 receivable into groove 70 so that the cover canbe inserted to cover the deeper slot portion 67 from face 66. `Cover 71 has a transparent -center 73 through which the interior of the deeper slot portion may be viewed after the cover is in place. A level capsule 75 is cemented or glued in place within the deeper slot portion, the end seal nipple 76 of the capsule fitting within offset 68. Cover 71 covers the capsule and the bubble 77 and index line 78 of the capsule can be observed through transparent center 73 of the cover to determine when the balance arm is level and therefore in correct balance.

Capsule 75 can be set in place in the deeper slot portion with a thin layer 80 of flexible cement, such as `a rubber cement, :applied beneath land `around the capsule, in which case the capsule is protected from shock and breakage by the resilience of rthe cement. Alternatively, layer 80 may be porcelain or other hard cement, such as Sauerisen cement, in which case the capsule is protected by its rigid setting. 'Il-1e use of a porcelain cement has ya `further advantage in that the porcelain reflects light from below the capsule and makes it easier to -read the level. Capsule 75 is ordinarily made of glass and contains immiscible liquid and gas to indicate true level in the conventional Way. Capsule 75 is additionally protected by cover 71, and should seldom be broken. However, should capsule 75 be' broken, a new capsule may be easily installed. The broken capsule and cement layer may be pried from the slot, after which a new capsule may -be set in the slot in the original manner and the cover 71 reinse-rted over the capsule. No screws or other threaded connection means are :required to hold the level indicating elements in place.

As indicated by FIGURE 8 of the drawings, the tubular end 16 of balance farm 11 also serves as a handle by means -of which the cup 10 may be manipulated to obtain sample-s of the drilling fluid. The arm and cup function as a dipper. After the cup is filled with drilling fluid as earlier described, and cleaned, knife edge 36 is set within fulcrurn groove 32, counterweight 40 `is slid p without departing from the spiri-t of the invention, and

it is intended to protect by Letters Patent all forms of the invention falling within the scope of the following claims: v

I claim:

l. An improved gravity balance comprising a bal-ance arm,

the portion of the balance arm extending inwardly from one end thereof constituting a cup supporting portion,

said cup supporting portion having an upwardly opening cup affixed to said one end,

the portion of said balance arm extending inw-ardly from the other end thereof constituting a weight supporting portion,

said weight supporting portion having a counterweight movably mounted thereon,

said weight -supporting portion being downwardly offset relative rto said cup supporting portion forming `a shoulder on Ithe upper side of said arm at the juncture of said portions,

said cup supporting portion having a pivot means on ythe underside thereof,

the upper side of said cup supporting portion of said balance arm having a slot therein adjacent said shoulder,

a spirit level capsule disposed in said slot,

and a panel for closing vthe top of said slot,

said cup supporting portion having a panel receiving groove around the top of said slot and extending therebeyond to said shoulder adapted slidably to receive said panel, said panel being insertable and re'- movable at the end of said slot adjacent said shoulder.

2. Apparatus according to claim l wherein said capsule is glued to the bottom of said slot.

3. Apparatus according to claim 1 wherein said pivot means is an elongated knife edge member of triangular cross section having plane sides, said cup supporting portion of said balance arm has a groove on the under side thereof, and said elongated knife edge member is removably press fitted in said groove.

4. An improved gravity balance including a receptacle,

a vented closure means to reduce the receptacle volume to a fixed amount,

a balance arm having a first end attached in integral relation to the receptacle,

a liquid filled level capsule disposed in externally viewable relation within the balance arm, said capsule being adapted to indicate a horizontal `disposition of,

said arm,

a pivot means disposed intermediate the length of said arm, said pivot means being adapted for pivoted engagement with a complementary base,

a calibrated cylindrical second end portion of said arm having an axially disposed threaded bore extending to the terminus of said end defining a chamber totally closed except at said end,

threaded taring weight fitted within said bore in axially adjustable relation to said arm, said taring weight being connected solely to said threaded bore,

a cylindrical counterweight eccentrically disposed about said cylindrical end portion in close fitting reciprocative relation whereby said end portion may be cleaned of foreign material by movement of said counterweight,

and a retaining means removably connected to said second cylindrical end in longitudinal retaining relation to said counterweight and in closing relation with said chamber.

5. An improved gravity balance including a receptacle,

a vented closure means to reduce the receptacle Volume to a fixed amount,

la first end of a balance arm attached in integral relation to the receptacle,

a liquid level capsule viewably disposed in internal relation with the balance arm, said capsule being adapted to indicate a horizontal disposition of said arm,

a pivot means disposed intermediate the length of said' arm, said pivot means being adapted for pivoted engagement with a complementary base,

a cylindrical second end portion of said arm defining an enclosable chamber extending to the terminus of said end,

a weight fitted within said chamber in longitudinally adjustable relation to said arm,

la counterweight disposed about said cylindrical end in close fitting reciprocative relation,

and retaining means disposed at said second cylindrical end in retaining relation to said counterweight, said retaining means also totally closing said chamber and preventing `adjustment and accidental displacement of said weight therein.

6. An improved gravity balance, comprising,

a balance arm,

level means on said arm to indicate horizontal disposition of said arm,

pivot means on said arm dividing the arm into a receptacle supporting portion at one side of said pivot means and a weight supporting portion at the other side of said pivot means,

a receptacle rigidly connected to said receptacle supporting portion of the balance arm,

a counter weight on said weight supporting portion movable therealong between a first position nearer to .the pivot means and a second position nearer to the end of said weight supporting portion farthest from said pivot means,

the portion of said balance arm between said first position and said second position constituting the counterweight travel portion of the balance arm,

a bore extending inwardly from said end of said weight supporting portion of the balance arm toward said pivot means,

said bore having an internally threaded portion disposed within said weight travel portion of said arm,

a taring weight in the form of a slug inserted in said bore and having a maximum diameter conforming to the inside diameter of said bore,

the portion of said slug having the maximum diameter being threaded its full length correlative to said threaded portion of the bore,

said slug lying entirely within said bore,

threaded removable closure means at the end of said weight supporting portion of the balance arm to totally close said bore,

said closure means being unconnected to said slug,

said balance arm including an offset in the Weight supporting portion thereof forming a stop limiting the travel of said counter-weight at said first position, and

said threaded closure means for the bore receiving the taring weight also providing a stop for said counterweight at said second position thereof.

7. Combination of cl-aim 6 wherein said weight travel portion of said balance arm is cylindrical concentric with said bore that receives said taring weight,

said weight travel portion having graduations therealong adjacent the top thereof,

said counter weight has a cylindrical aperture correlative to the cylindrical shape of said weight travel portion of lthe balance arm but eccentrically disposed relative to the center .of grav-ity of the counter weight,

whereby said weight travel portion of said balance arm is cleaned of foreign material by movement of said :counterweiglht along said weight travel portion of the `said arm exposing said graduations and said counter Weight gravitation to a position Where its thinnest Wall is at the top adjacent said graduations to facilitate determination of the position of an edge of said counterweight relative to said Weight travel portion of the balance arm.

' 8. An improved gravity balance including,

la receptacle in the form of a cup having a circular lip,

a cover for said cup having a portion telescopically engaging said lip,

`a balance arm having a first end attached in integral relation to the receptacle,

a liquid level capsule adapted to indicate a horizontal disposition of said arm xedly disposed thereon in viewable position,

a pivot means disposed intermediate the length of said arm, said pivot means being adapted for pivoted engagement with a complementary base,

a portion of said arm having an exterior surface that is cylindrically curved, said portion defining an enclosable chamber extending to the terminus of the arm at a second end thereof opposite from said rst end,

a taring Weight tted Within said chamber in longitudinally adjustable relation to said arm,

'a ycounter-weight disposed on said arm in reciprocative relation to said cylindrically curved portion of the tarm,

means disposed at said second end of said arm closing said chamber to prevent accidental displacement of said taring Weight therein, the last said means being unconnected to said taring weight,

the portion of said chamber Within which said taring weight is fitted being internally threaded,

`said'taring Weight being in the form of a slug having a maximum diameter conforming to the inside diameter of said threaded portion of said chamber,

the portion of said slug having the maximum diameter lbeing threaded its full length correlativo to said threaded portion of the chamber,

said slug lying entirely Within said chamber.

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